Lasers emit light in response to a current. For example, laser diodes produce light in response to a current in the diode. Also for example, semiconductor lasers also produce light in response to a current. The output radiance of a laser varies as the drive current is varied. The output radiance of a laser may also vary due to other factors. For example, the output radiance of a laser diode may vary with age. Also for example, the output radiance of a laser diode may vary as the temperature of the diode varies. This can be problematic in part because the temperature of a laser diode may be affected by ambient temperature changes as well as the historical drive current which results in “self-heating” of the diode.